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The Science Behind Revere, Mass.' Tornado

Find out why there wasn't much of a warning to the freak tornado touchdown on Monday (Published Thursday, July 31, 2014)

Monday's tornado in Revere, Massachusetts, wasn't the only touchdown of the day - in fact, it was one of four tornadoes to strike New England Sunday and Monday, with Wolcott, Connecticut and Dalton, Massachusetts, hit Sunday, and Limington, Maine, hit as well as Revere on Monday, bringing the total number of New England tornadoes so far this year to five.

The Revere tornado was a special kind since it was very different from what we see in storm chasing videos and in the movies - a tornado camoflagued by a blanket of heavy rain that spun up quickly, moved with little detection, and dissipated, all in four minutes.

By now the result of Monday morning's tornado in Revere, Massachusetts have been seen - rooftops ripped off, homes and businesses damaged, trees uprooted and snapped. This North Shore community of 52,000 residents has seen battering blizzards and raging hurricanes, but added a new distinction Monday: Home to the first Suffolk County tornado touchdown in recorded history, in what's termed a rain-wrapped tornado - a type of tornado that can sometimes deliver notoriously little or no warning.

The storm began from a piece of upper level atmospheric energy moving east out of the Great Lakes. As the energy collided with humid, warm air, thunderstorms developed, intensifying in Southern New England Monday morning.

By 8:20 a.m., some one hour and 12 minutes before the tornado, a weak rotation, not strong enough to produce a tornado, was evident within the storms on radar imagery as they approached Boston's MetroWest region.

By 9:30 a.m., after an hour and 10 minutes of tracking the storm, there was widespread flash flooding but not a single report of damage or strong wind, and radar indicated rotation weakened somewhat, expiring the severe thunderstorm warning.

Two minutes later, hidden in a blanket of torrential rain, the funnel descended and four minutes of terror in winds up to 120 mph ensued.

Within minutes, debris was detected on radar, reports of damage streamed in and a tornado warning was issued while coverage continued live, on-air, with street-by-street forecasts of the funnel. By that time, the tornado had already come and gone. Cars had been overturned, and citizens in impacted parts of town were contending with downed power lines amidst a gauntlet of downed trees, overturned cars and flooded roadways.

In a humid, tropical airmass, the cloud base hung low to the ground. What may otherwise be a funnel that can be observed in the sky, descending as it prepares to touch down, is instead embedded entirely in the cloud, enshrouded and hidden by rain and can touch down almost as quickly as it develops. In New England, it is the setup that affords the least advance warning for developing tornadoes.

And the Mayor of Revere echoed that sentiment.

"You know, it would have been nice to know, you know, to get people out of harm's way, but as it worked out, we didn't have to thankfully worry about that," Mayor Dan Rizzo said.

Thankfully, there were no serious injuries with this sudden tornado strike in a populated center just five miles north of Downtown Boston, but this event unquestionably serves as notice: While technology has propelled us to a point where we can provide unprecedented lead time on weather events - and in this case, on NECN, over an hour of early warning as the storm was rotating - there will continue to be sudden phenomenon, requiring the quick community response Revere officials exemplified.

From a forecasting perspective, this storm reminds meteorologists and viewers alike of inherent uncertainty in nature, of the importance storm information be expressed with a range of possible outcomes made clear, and those possible outcomes taken seriously. Occasionally, false alarms will sound when it comes to weather, but when potential events are realized, the impacts can be extreme.

From a meteorologist's perspective, this storm is a reminder of how critically important it is to convey all possibilities to our viewers - that effective early warning is the key - when tracking severe weather. Even when storms weaken, there is always the potential they will strengthen again, and even when rotation in a storm appears to subside, in a matter of minutes it can return - and it may not wait to put a tornado on the ground.

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